Relief grinding apparatus



March 12, 1963 G. STADE ET AL 3,080,584

, RELIEF GRINDING APPARATUS Filed April 24, 1962 4 Sheets-Sheet 1' INVENTORS GQRHARD STADE GUNTER REPPIN 51% and Fm ATTORNEYS.

March 12, 1963 G. STADE ETAL 3,080,684

RELIEF GRINDING APPARATUS Filed April 24, 1962 4 Sheets-Sheet 2 FIG. 2.

INVENT s GEBHAR TADE Y- GUNTER REPPIN AT TORNEYS.

March 1-2, 1963 s. STADE ETAL 3,080,684

RELIEF GRINDING APPARATUS Filed April 24, 1962 4 Sheets-Sheet 3 FIG. 3.

INVENTORS GE RHARD STA GUNTER REP 11% Mad 731m ATTORNEYS.

March 12, 1-963 G. STADE EI'AL 3,080,684

RELIEF GRINDING APPARATUS Filed April 24, 1962 4 Sheets-Sheet 4 FIG. 4.

INVENTORS GIE RHARD STADE GUNTER REPPIN WW mm! [m ATTORNEYS.

United States Patent'ofilice 3,80,684 Patented Mar. 12, 1963 3,il80,684 RELIEF GRIN ENG APPARATUS Gerhard Stade, Berlin, and Giinter Reppin, Berlin-Neulrolln, Germany, assignors to Firrna Herbert Lindner, Berlin-Wittenau, Germany Filed Apr. 24, 1962, Ser. No. 189,922 Claims priority, application Germany Apr. 28, 1961 12 Claims. (Cl. 51-45) This invention relates to relief grinding apparatus such as used, for example, to relief grind tools of the nature of tap drills, milling cutters and other like tools wherein the relief grinding is effected by relative lateral displacement of a grinding disk and the workpiece, this displacement being effected by a control cam rotatable with a control shaft and engaged by cam follower means on a pivoted lever operatively arranged to eifect relative displacement of the grinding wheel and the work. More particularly, the present invention is directed to an improved control cam means and follower lever arrangement involving a pair of cam followers, such as rollers,

which are mounted on inter-connected levers, and to novel means for bodily lifting both cam followers away from the control cam means simultaneously.

In known arrangements for effecting the relative displacement of the grinding wheel and the work during relief grinding and involving a rotatable cam, there is a. disadvantage that the angular velocity of the control cam cannot be increased at will to increase the output or the speed of operation. This is due to the fact that, if the angular velocity of the control cam is increased, then the follower roller, which is mounted on a lever and engages the cam, will not follow exactly along the cam surface but has a tendency to jump away from the latter. Consequently, there occurs, within the movement mechanism controlling the relief grinding movement, impacts, shocks and jolting which have a deleterious effect on the bearings so that the latter may be damaged or even destroyed. Due to this tendency of the follower roller to jump, there is a very rough and inaccurate grinding effect. Consequently, it is necessary to maintain the speed of operation below a predetermined value such that the angular velocity of the control shaft carrying the control cam is not so great that the follower roller will tend to jump from the periphery of the cam, and of such a low value that no jolting or impacts will occur.

if, for example, a four-lip tapping drill having four cutting edges is to be ground, then the grinding disk has to perform four relief grinding operations during each revolution of the workpiece, one relief grinding operation being performed upon each cutting edge. In each operation, the grinding disk is moved longitudinally of the workpiece, through a working stroke, in a given direc tion along the length of the cutting edge, and at the end of this longitudinal movement the grinding table must be rapidly returned to its starting position in a reversely directed return stroke. This rapid return movement takes place at a rate which is about five times as fast as the rate of movement during the working stroke so that, in turn, the control disk or cam is rotated five times as fast as during the working stroke. It is during this relatively high speed return stroke, during which the angular velocity of the control cam is about five times its angular velocity during the Working stroke, that the undesirable jolts, impacts, and irregular movements occur because of the follower roller jumping or lifting ofi the periphery of the control cam. Consequently, it is absolutely necessary, during the return stroke of the grind ing table, to lift the follower roller from the cam, and this is well known in the art.

An object of the present invention is to provide an arrangement of this type wherein the cam follower means can be lifted from the cam means during the return stroke while still providing that the angular velocity of the control cam means during the Working stroke can be very substantially increased to increase the output of the machine without the occurrence of impacts, jolting, or the like of the follower lever means.

The principal object of the invention is to provide such an arrangement in which two control cams, which are identical mirror copies of each other, are arranged in axially adjacent relation on the control shaft in mir ror relation to each other and relatively offset, each of these earns being engaged by a respective cam follower, such as a roller, mounted on its individual lever.

With an arrangement of this type, the distance between the two cam followers remains constant during the rotation of the two control cams.

A further object of the invention is to provide an arrangement of the foregoing type in which one of the lever is relatively fixedly mounted while the other lever is relatively adjustably mounted, and in which the two levers are interconnected by an articulated coupling so that the cam followers of both levers can be lifted together from the respective control cams. I

The relatively lateral movement between the grinding disk and the workpiece may be elfected either by maintaining the workpiece stationary insofar as lateral movement is concerned and moving the grinding disk laterally,

or vice-versa, in which latter case the grinding table can be tilted by means of an eccentric.

Yet another object of the invention is to provide a mounting arrangement for the grinding disk in which the shaft of the grinding disk is mounted in an eccentric which is, in turn, angularly adjusted by the adjusting mechanism for the relief grinding movement. 1

In further accordance with the invention, it has been found that a constant speed of the relief grinding movement can advantageously be effected by employing, for the control cams, cams which have surfaces in the form of an archimedic spiral, rather than employing a simple eccentric. In accordance with the invention, two such archimedic spiral cams are employed, arranged at an angular spacing to each other and being identical mirror copies of each other. The cam surfaces are sodesigned that, at the transition area, the condition is met that the distance between the follower rollers remains constant at all times. By virture of this latter arrangement, during the entire rotation of the dual control cams, there is effected a positive contact between the follower rollers and the peripheries of the cams, and this remains true even when the angular velocity of the control shaft is raised substantially beyond normal values. Despite this,

' and in accordance with the invention, both follower rollers can be disengaged from their respective cams during the return stroke of the grinding mechanism.

Still a further object of the invention is to provide an arrangement in which one of the levers is mounted on an angularly adjustable eccentric which may be angularly adjusted through 180 and, as a result of this angular adjustment and in association with other novel compoother position of the rack, both of the follower rollers are disengaged from the respective control cams.

Still another object of the invention is to provide an arrangement of the type just described in which the lifting movement of one of the levers with respect to its associated cam is limited by a stationary abutment engaged 3 thereby before the adjusting eccentric has reached its limit of movement in the lever lifting direction, as a result of which further movement of the eccentric eifects a lifting of the other follower roller from its associated cam.

As an alternative, the adjustably mounted roller lever could be mounted on a slide which is adjustable either hydraulically, electrically or magnetically, for adjustment of the lever pivot in the same manner as effected by the eccentric.

It will be understood by those skilled in the art that, before the return stroke of the grinding mechanism is initiated, the grinding disk has to be completely disengaged from the workpiece. Advantageously, in accordance with the present invention, disengagement of the grinding disk from the workpiece can be effected in response to the lifting of the follower rollers from the control cams. Such movement or disengagement of the grinding disk from the workpiece can be effected in any desired manner by means actuated by one of the levers as the two rollers reach the limit of their movement away from the respective control cams. By utilizing a control arrangement of this type, it can be assured that both rollers are completely disengaged from their respective cams before the high speed return stroke of the grinding mechanism is started.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a somewhat diagrammatic or schematic perspective view of a relief grinding apparatus having the inventive control cam control incorporated therein;

FIG. 2 is a transverse sectional view through a portion of the relief grinding apparatus, to an enlarged scale, and illustrating the cam control mechanism for the grinding wheel in the position in which the grinding wheel or disk is engaged with the workpiece;

FIG. 3 is a view similar to FIG. 2 illustrating the mechanism with the follower rollers disengaged and the grinding disk withdrawn from the workpiece;

FIG. 4 is a partial plan view, partially in section, of the portion of the apparatus shown in FIGS. 2 and 3; and

FIG. 5 is a sectional view illustrating the hydraulic actuator mechanism for operating the lever adjusting eccentric.

Referring first to FIG. 1, in the schematically illustrated' relief grinding apparatus, there is a drive motor 101 which, through belts 102, drives gearing contained in the gear box 103. The gearing in the gear box 103 includes an output gear 91, which through gearing illustrated at 92 and 93, rotates a drive shaft 104 for the control shaft 18, the driving connection between shaft 104 and shaft 18 being eifected by gears illustrated generally at 110. The control shaft 18 operates the control cams which, in turn and through the follower rollers and associated levers, as described more fully hereinafter, control the lateral movement of the grinding disk with respect to the workpiece. The gear 93 is further meshed with a gear 94 fixed to rotate with an axially elongated cylindrical gear 105 which is fixedly connected to rotate the workpiece guiding spindle 106. The spindle 106 is threaded and is engaged by a nut 107 so that, upon rotation of the shaft 106, the nut 107 will be moved longitudinally thereof. Through gearing indicated generally at 95, 96 and 97, the cylindrical gear 105 drives the workpiece spindle 108 which is rotatable in bearings in the grinding table 109.

The workpiece spindle 108 supports the workpiece 1, and the grinding table 109 is reciprocated longitudinally by virtue of its connection to the nut 107 engaged with the threaded shaft 106. The arrow a indicates the direction of the working stroke, whereas the arrow b indicates the direction of the high speed return movement or return stroke when the grinding. disk is disengaged from the workpiece. The relief grinding operation is effected by relative movement of the grinding disk 3 and the workpiece 1 laterally of each other, with the arrow c indicating the working stroke of the relief grinding movement while the dotted arrow d indicates the return or retraction stroke of the grinding disk.

During the axial reciprocation of the grinding table 109, the gearing associated with the grinding table, as well as the small gear 95, moves with the table and the grinding disk. It is for this reason that the cylinder gear 105 must have a length corresponding to the length of the grinding stroke in an axial direction. It will be observed that the cylinder gear 105 and the guide spindle 106 do not move with the grinding table but are fixedly positioned, against longitudinal movement, in the apparatus.

The cam control mechanism embodying the invention is shown at the right in FIG. 1. Referring more particularly to FIGS. 2 and 3, the workpiece is illustrated, by way of example, as a tap drill 1 having four cutting edges. In order to relief grind tools such as tap drills, resort is generally had to single profile grinding disks 3 as shown in FIGS. 2 and 3. The workpiece 1 is mounted in the grinding table 2 which, as explained, is movable relative to the grinding disk 3 in a longitudinal direction which is parallel to the axis of rotation of the grinding disk. The spindle or axis 4 of the grinding disk is rotatable in an eccentric bushing 5 which is mounted in a bore of the box 6, in which it is rotatable but held against axial displacement. Rotation of the eccentric bushing is effected by means of a clamp 7 which embraces this bushing. Clamp 7 has an extension or lever arm 8 to which is connected a tension spring 9 whose tension is adjustable by means of a set screw 10 connected to the other end thereof and adjustable in a fixed portion of the apparatus.

Lever portion 8 is connected, by means of a universal joint type of connection, to a connecting rod 12, 12 whose length is adjustable by means of a turnbuckle 80. For this purpose, a bolt 81 is adjustably secured in the arm 8 and has a ball on its lower end which is engaged between spherical seat members 82, 83 which are disposed in a housing 11 and maintained therein by a nut element 88 secured to one of the rods 12. A lock nut 13 maintains the parts againt displacement. As indicated at 11a and 13a, a similar type of universal joint connection conmeets the lower rod 12 to one arm 14 of a crank or angular lever 1415, which is rotatable on an axle or shaft 16. A forked coupling 84 is secured to the outer end of the other arm 15 of the lever 1415, and is pivotally coupled to one end of an adjustable rod member 37 which is adjustable by means of a turnbuckle 86. It should be noted that the lever arms 14 and 15 are offset axially from each other, for a purpose to be described, and that the axle or pin 16 of the lever arm is fixedly mounted in the grinding apparatus.

A bearing bushing 17 is mounted in the apparatus and is formed with a flange 87, as best seen in FIG. 3. Bushing 17 rotatably supports the control shaft 18 which has a forward end projecting beyond the bearing bushing 17. The shaft 18 may be further rotatably supported by means of a reduced diameter portion 18a which is mounted in a bearing bushing 88. Forwardly of the flange 87 of the bearing bushing 17, control cam disks 19 and 20 are secured to the control shaft 18 so that they will rotate with the latter. The control cam disks 19 and 20 are spaced axially from each other, as by means of spacers or washers 21, and are held in assembled relation by means of a pair of nuts 22. The control cam disks 19 and 20 are mirror copies of each other, and these disks have archimedian peripheries, the two disks 19 and 20 being angularly offset on shaft 18.

A lever 23 is mounted for oscillation in the general plane of the front control disk 20, this lever being oscillatable about a pin or shaft 25 which is fixed in the flange 87. A roller 23a is rotatably secured on the end of the lever 23 which is pivotally secured to the adjustable rod member 37, and roller 23a is continuously engaged with the periphery of the cam 20. A second lever 24 is oscillatable in the general plane of the other cam disk 19, and rotatably carries a roller 24a which is continuously engaged with the periphery of the cam 19.

The lever 24 is mounted for what may be termed bodily displacement by suitable means, indicated in FIGS. 2 and 3 as an eccentric 26 which is angularly adjustable about a stationary shaft or pin 27 by a sleeve 28. Sleeve 28 has fixed thereto a gear 29 which is meshed with a rack 30 which, as best seen in FIG. 5, constitutes an extension of apiston rod 31 secured to a piston 32 movable in a hydraulic cylinder 33. Pipe lines 34 and 35 supply hydraulic operating fluid to the cylinder 33 above and beneath the piston 32. These pipe lines 34 and 35 comprise supply and discharge lines which are selectively operable under the control of suitable control mechanism to move the piston 32 in selected directions longitudinally of the cylinder 33.

The opposite ends of the levers 23 and 24 are interconnected by an adjustable link or rod 36 whose length is adjustable by means of a turnbuckle 87, the opposite ends of the members 36 being pivotally secured to the ends of the levers 23 and 24. The distance between these ends of the levers 23 and 24 is adjusted, by means of the turnbuckle 87, so that it is equal to the distance between the axes of rotation of the rollers 23a and 24a, which distance remains constant as the length of the diameter through the control shaft 18 and terminating at the surfaces of the cams 19 and 20 is constant for all rotational positions of the control shaft 18 with the cam disks 19 and 2t) thereon, the two rollers 23a and 24a are constantly engaged with the peripheries of their respective cam disks 20 and 19.

It will be noted that there is a stationary abutment 38 provided adjacent that end of the lever 24 carrying the roller 24a. Such end of the lever 24 engages the adjustable abutment 38 when the eccentric 26 is rotated in a given direction to move the axis of oscillation of the lever 24 in a direction such as to disengage its roller 24a from its associated cam disk 19. This engagement of the end of lever 24 with the abutment 38 occurs before the eccentric 26 has completed the full extent of its angular adjustment and, as the angular adjustment of the eccentric 26 continues, the lever 24 will pivot clockwise about its engagement with the abutment 38 so as to swing the lever 23 clockwise about the axis of its mounting shaft 25 to disengage roller 23a from its associated cam disk 19. This disengaged position is best shown in FIG. 3 of the drawing.

It will further be noted that, due to the clockwise rotation of the lever 23, the adjustable length rod member 37 is moved to the right, thus swinging the lever 14-15 about the axis of the pin 16. In turn, this moves the adjustable length rod member 12 downwardly and swings the clamp 7, through the lever arm 8, in a clockwise direction to rotate the eccentric sleeve 5 about the pin 4. This retracts the grinding disk 3 from the workpiece 1. Such disengagement or lifting of the rollers 23a and 24a from the periphery of the associated cam disks occurs prior to the start of the return stroke of the grinding table, so that this return stroke can be made at a very rapid rate without any ill effects due to the fact that the rollers are disengaged from the cams.

Referring to FIG. 4, it will be appreciated that such disengagement of the rollers from their cam disks as well as the reengagement of the rollers with the cam disks can be effected by the hydraulic mechanism 31--32. As piston 32 moves axially, the rack 30 rotates the gear 29 to, in turn, rotate the eccentric 26 about the sleeve 28.

The sequence of operations is essentially as follows: First, the grinding disc 3 is moved into engagement with the workpiece, after which the working stroke is started so that the grinding disk moves to the left as viewed in FIG. 1. At the end of the working stroke, the rollers 23a, 24a are retracted from their respective control cam disk, in the manner described, and, at the same time, the grinding disk 3 is retracted from the workpiece 1. The grinding table is then conditioned for the high speed or return stroke in which the grinding wheel is disengaged from the work and the cam follower rollers are disengaged from the cams. At the end of the return stroke, the cam followers are reengaged with the respective control cams and the grinding disk is reengaged with the work, after which the working stroke of the grinding table is repeated.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In relief grinding apparatus of the type including a rotatable grinding disk having an axis of rotation in spaced parallel relation to a workpiece, the grinding disk and the workpiece being relatively reciprocable longitudinally of such axis of rotation during alternating working and return strokes, and the workpiece and the grinding disk being relatively movable laterally of the direction of reciprocation under the control of cam follower means engaged with cam means rotatable with a control shaft; the improvement comprising, in combination, a pair of control cams, which are mirror copies of each other, fixed in axially spaced relation on said control shaft and angularly relatively displaced to the extent that the distance, diametrically of the control shaft, between diametrically opposed points of the peripheries of the two cams, is constant at all angular position; a pair of levers each oscillatable, in the general plane of a respective associated cam, about an axis intermediate the lever ends; a pair of cam follower means, each at one end of a respective lever and continuously engaged with the periphery of the associated cam at an end of a diameter of the control shaft; means interconnecting the opposite ends of the levers and maintaining said opposite ends at a fixed spacing for conjoint oscillation of said levers; means selectively operable to bodily shift the axis of oscillation of one lever to disengage its cam follower means from the associated cam; and means, including said interconnecting means, operable, responsive to such shifting, to swing the other lever about its axis of oscillation to disengage its cam follower from its associated cam.

2. The improvement in relief grinding apparatus, as claimed in claim 1, in which said selectively operable means is operable to bodily shift such axis of oscillation following the termination of a working stroke and in advance of the initiation of the return stroke.

3. The improvement in relief grinding apparatus, as claimed in claim 1, in which each cam follower means comprises a roller rotatably mounted in one end of the associated lever,

4. The improvement in relief grinding apparatus, as claimed in claim 3, in which said interconnecting means is an adjustable length rod means pivotally connected at each end to such opposite ends of the levers; said rod means being adjustable so that the distance between its two pivotal connections is equal to the distance between the axes of the rollers.

5. The improvement in relief grinding apparatus, as claimed in claim 3, in which said cams are disks having peripheries in the form of archimedian spirals.

6. The improvement in relief grinding apparatus, as claimed in claim 1, in which said selectively operable means includes an eccentric on which said one lever is oscillatable.

7. The improvement in relief grinding apparatus, as claimed in claim 6, including a gear coaxial with and rotatable with said eccentric; and means selectively operable to rotate said gear to rotate said eccentric to shift such axis of oscillation of said one lever.

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8. The improvement in relief grinding apparatus, as claimed in claim 7, including a rack engaged with said gear; and hydraulic actuator means operable to reciprocate said rack to effect such bodily shifting of the axis of oscillation of such one lever.

9. The improvement in relief grinding apparatus, as claimed in claim 8, in which, at one limit of reciprocation of said rack, said rollers are engaged with the associated cams and, at the other limit, said rollers are disengaged from the associated cams.

10. The improvement in relief grinding apparatus, as claimed in claim 9, in which said cam follower means comprise a pair of rollers each rotatably mounted in such one end of a respective lever.

11. The improvement in relief grinding apparatus, as claimed in claim 1, including an abutment engaged by said one end of said one lever during such bodily shifting of the axis of oscillation thereof, whereby, upon further shifting of the axis of oscillation thereof, said one lever will be pivoted about said abutment to so swing said other lever about the axis of oscillation of the latter.

12. The improvement in relief grinding apparatus, as claimed in claim 1, including means connected to such other lever and operable, responsive to such swinging of the other lever about its axis of oscillation, to effect such relative lateral displacement between the workpiece and the grinding disk; said selectively operable means being so operable following the termination of the working stroke and in advance of the initiation of the return stroke; whereby said cam followers are disengaged from the associated cams, and said grinding disk is disengaged from the workpiece, during the return stroke.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN RELIEF GRINDING APPARATUS OF THE TYPE INCLUDING A ROTATABLE GRINDING DISK HAVING AN AXIS OF ROTATION IN SPACED PARALLEL RELATION TO A WORKPIECE, THE GRINDING DISK AND THE WORKPIECE BEING RELATIVELY RECIPROCABLE LONGITUDINALLY OF SUCH AXIS OF ROTATION DURING ALTERNATING WORKING AND RETURN STROKES, AND THE WORKPIECE AND THE GRINDING DISK BEING RELATIVELY MOVABLE LATERALLY OF THE DIRECTION OF RECIPROCATION UNDER THE CONTROL OF CAM FOLLOWER MEANS ENGAGED WITH CAM MEANS ROTATABLE WITH A CONTROL SHAFT; THE IMPROVEMENT COMPRISING IN COMBINATION, A PAIR OF CONTROL CAMS, WHICH ARE MIRROR COPIES OF EACH OTHER, FIXED IN AXIALLY SPACED RELATION ON SAID CONTROL SHAFT AND ANGULARLY RELATIVELY DISPLACED TO THE EXTENT THAT THE DISTANCE, DIAMETRICALLY OF THE CONTROL SHAFT, BETWEEN DIAMETRICALLY OPPOSED POINTS OF THE PERIPHERIES OF THE TWO CAMS, IS CONSTANT AT ALL ANGULAR POSITION; A PAIR OF LEVERS EACH OSCILLATABLE, IN THE GENERAL PLANE OF A RESPECTIVE ASSOCIATED CAM, ABOUT AN AXIS INTERMEDIATE THE LEVER ENDS; A PAIR OF CAM FOLLOWER MEANS, EACH AT ONE END OF A RESPECTIVE LEVER AND CONTINUOUSLY ENGAGED WITH THE PERIPHERY OF THE ASSOCIATED CAM AT AN END OF A DIAMETER OF THE CONTROL SHAFT; MEANS INTERCONNECTING THE OPPOSITE ENDS OF THE LEVERS AND MAINTAINING SAID OPPOSITE ENDS AT A FIXED SPACING FOR CONJOINT OSCILLATION OF SAID LEVERS; MEANS SELECTIVELY OPERABLE TO BODILY SHIFT THE AXIS OF OSCILLATION OF ONE LEVER TO DISENGAGE ITS CAM FOLLOWER MEANS FROM THE ASSOCIATED CAM; AND MEANS, INCLUDING SAID INTERCONNECTING MEANS, OPERABLE, RESPONSIVE TO SUCH SHIFTING, TO SWING THE OTHER LEVER ABOUT ITS AXIS OF OSCILLATION TO DISENGAGE ITS CAM FOLLOWER FROM ITS ASSOCIATED CAM. 